Have an older Japser with the transistor JTAG. Just went RROD 0022. I am guessing Nand corruption.
I have the Nand-X reader JTAG kit from a while back.
a-solder in the Nand-x and reflash the nand back to stock and start over
b-Install the Nand-x and jtag without removing the old one?
c- remove the three wires from the old JTAG and install the Nand-x as per the tut?